It's not a good idea to take it long-term, according to our medical advisors. Tylenol PM contains two medications—the pain reliever acetaminophen and an antihistamine (diphenhydramine) to help with insomnia. High doses of acetaminophen can cause liver damage and the risk increases if you consume alcohol. Possible side effects of diphenhydramine include daytime sleepiness, confusion, constipation, dry mouth, and urinary retention and it can worsen your sleeping problems when taken too often.
If you're taking Tylenol PM to help you get to sleep—three or more nights a week for a month or more—a better option to treat your insomnia might be working with your doctor to undergo behavioral therapy training. This involves working with a therapist to learn a new set of sleep behaviors. For example, you might be directed to get up at the same time every day and learn relaxation techniques and mental tricks to help you get to sleep. Studies have found behavioral therapy to be effective—it helps 70 to 80 percent of people with chronic insomnia—and it appears to be at least as effective as sleeping pills.
If you suffer from chronic pain such as arthritis, and use Tylenol PM to treat it, talk to your doctor about non-medication options. Regular exercise, losing weight if necessary, and stretching might eliminate or reduce the need to take medicine. If you still need to take acetaminophen for additional pain relief, be careful to avoid high doses. Never take more than the maximum daily amount—4,000 mg or the equivalent of eight extra-strength 500 mg capsules. Acetaminophen can cause liver problems even at doses lower than 4,000 mg per day, so only take as much as you need. To learn more about pain relievers, read our free Best Buy Drugs report on these medications.
For insomnia that you've only had a night or two, reassess your sleep routine before turning to medication. Are you watching TV or using computers, tablets or phones in bed? That can make it difficult to fall asleep, so switch them off long before you hit the sack. If you drink alcohol or caffeine, take your last sip at least 3 hours before bedtime. A comfortable mattress, covers and pillow can also help. And make sure your bedroom isn't too noisy, bright or hot. To learn more about insomnia medications and how to treat it, check out our free Best Buy Drugs report.
This article and related materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multistate settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).